Fallout: New Vegas

Glitches

Infinite Experience Glitch (Pre-Patch)

If your speech skill at 50 or higher, you can persuade Old Ben to offer his escort services to the local bar, if you succeed in the Speech Challenge, you'll gain 61 XP. If you follow him back to the bar afterwards and wait until he sits down, you can speak to him again and redo the same Speech Challenge over and over again for infinite XP! You can find Old Ben sitting by a fire close to The King's headquarters in Freeside.

Contributed By: Blk_Mage_Ctype.

Infinite XP (Pre-Patch)

You need Speech of 30 or the perk Confirmed Bachelor. You must also be on the good side of NCR. Go to HELIOS One and the lady should automatically talk to you. Once she allows you access HELIOS One, you should be able to start the mission "That Lucky Old Sun". Follow the mission and talk to Fantastic and Ignacio Rivas. While talking to Rivas make sure you get him to reveal that he's a Follower of the Apocalypse by using Speech or Confirmed Bachelor and agree with his ideals about peace or just say you're neutral. Do the mission regularly until you get to the point where you activate the Mainframe Terminal. Configure the Power Grid to "5) Full Region (Emergency Output Level). Finish the mission by hitting the Reflector Control Panel outside on top of the tower. Go back to Ignacio Rivas and choose the option "I overloaded the plant. No one.....". The glitch is that the option never disappears, so you can choose to keep pressing it.
You get 350XP, 3 Stimpacks, and 2 Doctor's Bag

Contributed By: papajag.

Infinite xp in Vault 11 (Pre-Patch)

Aftr reaching the sacrificial chamber and dispatching the robots go to the computer terminal through the previousley closed wall and enter it. The bottom option can be pressed over and over again to gain 500 xp each time. If any of the other options are chosen or the terminal is exited you cannot use the eploit again.